When bores are made into the earth for the purpose of obtaining fossil fuels such as oil and hydrocarbon gases, it is desirable to obtain and examine geological samples comprising rock cuttings or chips. From the samples obtained, a trained observer can elucidate whether hydrocarbons are present and also determine the lithic nature, kind and type of the subterranean reservoir containing the hydrocarbons. Current methods for obtaining these samples include vertical coring using drill pipe and appropriate coring equipment as well as side-wall horizontal coring methods such as explosive processes or other mechanical processes.
Under normal conditions, the bottom-hole pressure in a bore or hole drilled into the earth increases predictably at the rate of from 0.434 lb./s.i. to 0.450 lb./s.i. per foot of depth. For example, a hole drilled to 1000 feet will have a bottom-hole pressure in the range of from 434 to 450 p.s.i. The method of using the Geological Sample-Sub (GSS) of the current invention exploits this bottom-hole pressure at a drilled depth to implode the surrounding rock. Rock dislodged by this implosion may be passively caught and retained by the GSS until it is desired to remove and examine it to determine its lithic nature and/or hydrocarbon content. Moreover, the GSS achieves the goal of capturing the desired rock sample without impeding the flow of fluids and gases through an associated string assembly having attendant testing apparatus.